JPH06199123A - Vehicular suspension device - Google Patents

Abstract

PURPOSE:To restrict mainly the roll of a vehicle by changing and controlling the stroke side of a shock absorber whose direction is same as the direction on the sprung velocity of a wheel to a high attenuation coefficient until this direction is reversed when a steering angular velocity is more than a prescribed threshold value. CONSTITUTION:A shock absorber (b) having an attenuation coefficient change means (a) is arranged between a vehicular body and respective wheels on a vehicle. The sprung velocity of respective wheels and a vehicular steering angular velocity are detected by respective detection means (c), (d). When the steering angular velocity is less than a prescribed threshold value, the attenuation coefficient change means (a) is controlled by the attenuation coefficient control unit (e) of a control means (f) so as to change the shock absorber (b) most suitably based on the sprung velocity. Meanwhile, when the steering angular velocity is more than a prescribed threshold value, the attenuation coefficient change means (a) is controlled by a roll control unit (9) so as to change the stroke side of the shock absorber (b) whose direction is same as the direction of the sprung velocity of respective wheels, to a high attenuation coefficient until it is reversed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle suspension system for controlling a damping coefficient of a shock absorber provided between a sprung part and an unsprung part of a vehicle, and more particularly to a device for controlling roll suppression during steering.

[0002]

2. Description of the Related Art Conventionally, as such a vehicle suspension system, one disclosed in Japanese Utility Model Laid-Open No. 62-70008 is known.

In this vehicle suspension system, the roll angle of the vehicle is calculated from the vehicle speed detected by the vehicle speed detecting means and the steering angle detected by the steering angle detecting means, and this roll angle exceeds a predetermined threshold value. When the steering direction at that time is used as a reference, the damping coefficient of the shock absorber is controlled by controlling the expansion side to a high damping coefficient on the steering direction side and the compression side to a high damping coefficient on the opposite side to the steering direction. It was designed to suppress rolling of the vehicle.

[0004]

However, in such a conventional vehicle suspension system, the apparent roll state is judged based on the steering angular velocity and the steering direction detected by the steering angle detecting means. Therefore, there is no problem when the steering is single-shot, but when continuous steering such as slalom is performed, there is a phase difference between the roll angle calculated by the calculation based on the steering angular velocity and the actual roll angle of the vehicle. This causes the damping coefficient to be controlled in the direction opposite to the actual roll control direction, which in turn causes the roll to increase in length, impairs steering stability, and sets the damping coefficient irrespective of the direction of sprung speed. Therefore, there is a problem in that the input from the road surface is easily transmitted to the sprung part and the riding comfort is deteriorated.

The present invention has been made in view of such a problem, and suppresses the roll of the vehicle to ensure steering stability even during continuous steering such as slalom, and at the same time during roll control. It is an object of the present invention to provide a vehicle suspension device capable of ensuring the riding comfort of a vehicle.

[0006]

According to the present invention, as shown in the claim correspondence diagram of FIG. 1, it is provided between each wheel of the vehicle and the vehicle body, and one of the extension side and the compression side of the stroke side is highly damped. When controlling to the coefficient side, a shock absorber b having a damping coefficient changing means a having a structure in which the reverse stroke side has a low damping coefficient, a sprung speed detecting means c for detecting the sprung speed at each wheel portion, and a vehicle Steering angular velocity detecting means d for detecting the steering angular velocity of each wheel, and when the steering angular velocity detected by the steering angular velocity detecting means d is less than a predetermined threshold value, each wheel portion detected by the sprung velocity detecting means c. A control means f having a damping coefficient control part e for outputting a switching signal to the damping coefficient changing means a in order to control each shock absorber b to an optimum damping coefficient based on the sprung speed in
When the steering angular speed detected by the steering angular speed detecting means d provided in the control means f is equal to or more than a predetermined threshold value, the direction of the sprung speed in each wheel portion is passed after a predetermined time has elapsed from that point. Until the reverse rotation, the roll control unit for outputting a switching signal to each damping coefficient changing means a in order to control the stroke side of each shock absorber b having the same sprung speed direction of each wheel portion at that time to a high damping coefficient. and g.

[0007]

The function of the present invention will be described. The reference numerals in the description correspond to those in FIG. When a steering operation is performed while the vehicle is running, the vehicle body rolls. At this time, when the steering angular velocity detected by the steering angular velocity detecting means d is equal to or greater than a predetermined threshold value, a large roll is generated on the vehicle body by abrupt steering, and therefore the roll control unit g controls each wheel. Shock absorbers b in the same direction as the sprung speed
A switching signal is output to each damping coefficient changing means a in order to control each stroke side to a high damping coefficient, whereby the stroke side stroke of each shock absorber b corresponding to the actual roll direction of the vehicle body is suppressed. The transient roll of the vehicle body can be suppressed.

The roll control is performed after the steering angular velocity has once exceeded a predetermined threshold value and after a predetermined time has elapsed, until the direction of the sprung speed at each wheel portion is reversed. Maintained. This is because when abrupt steering is performed, the rolling of the vehicle body occurs at a point when a little time has passed after the steering angular velocity exceeds a predetermined threshold value, and the direction of the sprung velocity changes based on this rolling. To reverse
The roll control state is maintained when the sprung speed reverses first.

In this way, switching control of the damping coefficient of each shock absorber b is performed in correspondence with the actual rolling direction of the vehicle, whereby rolling of the vehicle is suppressed even for continuous steering such as slalom. It is possible to secure steering stability.

When the steering angular velocity is less than a predetermined threshold value, the roll control section g does not operate and the damping coefficient control section e detects the sprung speed, because the steady roll state occurs during the steady turn. Based on the signal from the means c, a switching signal is output to the damping coefficient changing means a in order to control the shock absorber b to the optimum damping coefficient, whereby the riding comfort of the vehicle during steady turn can be secured.

[0011]

Embodiments of the present invention will now be described in detail with reference to the drawings. First, the configuration of the embodiment will be described. FIG. 2 is a system block diagram of an embodiment of the present invention, in which 1 is a damping force type shock absorber, 2 is a pulse motor, 3 is a sprung acceleration sensor, 4 is a steering sensor, and 5 is a control unit. Shows.

A total of four shock absorbers 1 are provided between each of the four wheels and the vehicle body.

The pulse motor 2 switches the damping coefficient position of the shock absorber 1, and the damping coefficient position of each shock absorber 1 is changed in multiple steps by step driving.

The sprung acceleration sensor 3 is attached to a sprung vehicle body, and detects the vertical acceleration on the spring.
An electric signal corresponding to the detected sprung acceleration is output. The sprung acceleration sensor 3 is also provided for each shock absorber 1.

The steering sensor 4 constitutes a steering angular velocity detecting means and is provided in the steering wheel.
It outputs an electric signal according to the steering angle. Then, the steering angular velocity is calculated from the change in the steering angle.

The control unit 5 constitutes a control means, and in the damping coefficient control section thereof, based on the input signal from the sprung acceleration sensor 3, the shock absorber 1 is set to have an optimum damping coefficient. Motor 2
Output a control signal to the roll control unit,
In order to suppress the roll, the damping coefficient of each shock absorber 1 is controlled to be set higher on the stroke side. That is, the control unit 5 includes an interface circuit 5a, a CPU 5b, and a drive circuit 5c, and the output signals from the vertical acceleration sensor 3 and the steering sensor 4 are input to the interface circuit 5a, respectively.

Next, FIG. 3 is a sectional view showing the structure of the shock absorber 1. The shock absorber 1 is
A cylinder 30, a piston 31 defining the cylinder 30 into an upper chamber and a lower chamber B, an outer cylinder 33 having a reservoir chamber C formed on the outer periphery of the cylinder 30, a lower chamber B and a reservoir chamber C.
And a guide member 35 for guiding the sliding movement of the piston rod 7 connected to the piston 31.
A suspension spring 36 interposed between the outer cylinder 33 and the vehicle body, and a bumper bar 37.

More specifically, as shown in FIG. 4, the shock absorber 1 has a groove on the inside of the expansion side as a flow passage through which the fluid in the upper chamber A compressed in the extension stroke can flow to the side of the lower chamber B. The first and second expansion-side flow paths D that open the inner and outer peripheral portions of the expansion-side damping valve 12 from the position 11 to reach the lower chamber B;
An expansion side second flow path E that opens the outer peripheral portion of the expansion side damping valve 12 from the position of the expansion side outer groove 15 to the lower chamber B via the port 13, the vertical groove 23, and the fourth port 14; 2 port 1
3, the expansion side third flow path F reaching the lower chamber B by opening the expansion side check valve 17 via the vertical groove 23 and the fifth port 16
And a bypass flow passage G reaching the lower chamber B via the third port 18, the second lateral hole 25 and the hollow portion 19, and the inside of the lower chamber B compressed in the pressure stroke. Of the pressure side damping valve 20 as a flow path through which the fluid of FIG.
And the pressure side first flow path H reaching the upper chamber A and the hollow portion 1
9, the pressure side second flow path J which opens the pressure side check valve 22 via the first lateral hole 24 and the first port 21 to reach the upper chamber A, the hollow portion 19, the second lateral hole 25 and the third Port 18
There are three flow paths, the bypass flow path G and the bypass flow path G that reach the upper chamber A via the.

The vertical groove 23 and the first and second lateral holes 2 are also provided.
The adjuster 6 in which 4, 25 are formed can switch the position of the damping coefficient in multiple stages among the three positions shown in FIGS. 5 to 7 based on the step rotation by the driving of the pulse motor 2. .

First, in the second position shown in FIG. 5 (the position shown in FIG. 8), the expansion side first flow path D, the compression side first flow path H and the compression side second flow path J can flow. As a result, as shown in FIG. 9, the extension side has a high damping coefficient (see FIG.
+ Xmax position), the pressure side of the reverse stroke has a predetermined low damping coefficient (-Xsoft position in FIG. 12).

Next, at the first position (position in FIG. 8) shown in FIG. 6, the four flow paths D,
E, F, G and all of the three flow paths H, J, G of the pressure stroke are allowed to flow, and as a result, as shown in FIG. 10, both the expansion side and the compression side have a predetermined low damping coefficient. (± Xsoft position in FIG. 12).

Next, at the third position shown in FIG. 7 (the position shown in FIG. 8), the extension side first to third flow paths D, E, F are formed.
Also, the pressure side first flow path H is allowed to flow, and as a result, as shown in FIG. 11, the pressure side has a high damping coefficient (see FIG. 12).
-Xmax position), the extension side of the reverse stroke has a predetermined low damping coefficient (+ Xsoft position in FIG. 12). The first and third positions can be switched in multiple stages according to the step rotation angle of the adjuster 6, and only the damping coefficient on the high damping coefficient side is proportional to the step rotation angle. Can be changed.

That is, in the shock absorber 1, when the adjuster 6 is rotated, the damping coefficient based on the rotation has characteristics as shown in FIG. 12 on both the expansion side and the compression side. It is configured so that it can be changed in multiple steps within the range of high damping coefficient. In addition, as shown in FIG.
When the adjuster 6 is rotated counterclockwise from the position where both the compression side is set to the low damping coefficient (± Xsoft position in FIG. 12), only the extension side is changed to the high damping coefficient side, and conversely,
When the adjuster 6 is rotated clockwise, only the compression side changes to the high damping coefficient side.

Next, the operation flow of the damping coefficient position control in the control unit 5 will be described with reference to the flow charts shown in FIGS. 13 and 14.

First, in step 101 of FIG. 13, initial setting is performed, and in subsequent steps 102 and 103, the sprung speed V and the steering angular speed θn are respectively detected.

The following step 104 is a step for judging whether or not the steering angular velocity θn exceeds a predetermined threshold value θc. When it is equal to or larger than the predetermined threshold value θc (YES), the routine proceeds to step 105 and the roll control condition is satisfied. After turning ON, the process proceeds to step 106, where it is less than a predetermined threshold value θc (N
When it is O), the process proceeds to step 106 without turning on the roll control condition.

In step 106, the roll control condition is turned on.
In the step of determining whether or not a predetermined time T has elapsed after switching to the state, if it is the predetermined time T or more (YES), the process proceeds to step 107 and is less than the predetermined time T (N
If it is O), the process directly proceeds to step 109.

Step 107 is a step of judging whether or not the direction of the sprung speed V is reversed.
If the number of points has passed 0 (YES), the process proceeds to step 108 and the roll control condition is turned off, and then step 109
If the sprung speed V does not pass through the zero point (NO), the process directly proceeds to step 109.

In step 109, the roll control condition is ON.
If the roll control condition is the ON state (YES) in the step of determining whether the state is the state, step 110 of FIG.
If the roll control condition is OFF (NO),
It progresses to step 111 of FIG.

Step 110 is a step for judging whether the direction of the sprung speed is upward (V> 0), that is, the roll direction of the vehicle. When the direction is upward (YES), the process proceeds to step 112, and the sprung speed is increased. The target damping coefficient on the extension side, which is the same stroke side as the direction of, and the soft target damping coefficient on the compression side, which is the reverse stroke side, are set. After setting the target damping coefficient on the compression side, which is the same stroke side as the direction of, to hard and the target damping coefficient on the extension side, which is the reverse stroke side, to soft, the routine proceeds to step 114. That is, this step 110 is a step for controlling the stroke side of each shock absorber 1 to the maximum damping coefficient for roll control, and the hardware corresponds to the damping coefficient at the ± Xmax positions in FIG.
The soft corresponds to the damping coefficient at the ± Xsoft position in FIG.

Step 111 is a step for performing normal damping coefficient control when the vehicle is not in a rolling state. After calculating the target damping coefficient from the sprung speed V and the control gain, the routine proceeds to step 114.

In step 114, the control point of the pulse motor 2 is calculated based on each target damping coefficient, and in the following step 115, a signal is output to drive the pulse motor 2 toward the control point of the pulse motor 2. .

As described above, the control unit 5 repeats the above control flow.

Next, the operation of the embodiment will be described with reference to FIG. That is, FIG. 15 is a time chart for explaining the operation during traveling of the vehicle, and FIG. 15 (a) shows the steering angular velocity θn,
(B) is the roll control condition on the left wheel side, (c) is the sprung speed V on the left wheel side, (d) is the pulse motor control point on the left wheel side,
The figure (e) shows the roll control condition on the right wheel side, the figure (f) shows the sprung speed V on the right wheel side, and the figure (g) shows the pulse motor control point on the right wheel side.

(A) When the steering angular velocity is small As shown in FIG. 15a, the absolute value of the steering angular velocity ± θn |
When θn | does not exceed the absolute value | θc | of the threshold value ± θc, the roll generated by steering is also small. At this time, the ± Xhard position is based on the control gain that gives the maximum damping coefficient. Switching to normal damping coefficient control,
The damping coefficient position switching control is performed so that the stroke side of the shock absorber 1 in the same direction as the sprung speed ± V at that time has a high damping coefficient proportional to the sprung speed ± V. That is, a) The absolute value | θn | of the steering angular velocity ± θn is less than the absolute value | θc | of the predetermined threshold value ± θc, and the sprung velocity V is
Is upward (+), the extension side, which is in the same direction as the sprung speed V at that time, has a high damping coefficient position proportional to the sprung speed + V, and the opposite compression side has a predetermined low damping coefficient. Switch to the second position (position in FIG. 8 and FIG. 9) which is (-Xsoft position).

B) The absolute value of the steering angular velocity ± θn | θn | is less than the absolute value | θc | of the predetermined threshold value ± θc, and
When the direction of the sprung speed V is downward (-), the pressure side, which is in the same direction as the direction of the sprung speed V at that time, has a high damping coefficient position proportional to the sprung speed -V, and the opposite expansion side is Switching to the side of the third position (position of FIG. 8 and FIG. 11) where a predetermined low damping coefficient (+ Xsoft position) is achieved.

Therefore, the roll generation state is predicted by detecting the steering angular velocity, and when the roll is unlikely to become violent, that is, when the steering angular velocity is slow, in a steady turn, the direction of the sprung velocity ± V at that time is the same. By controlling the stroke direction side of the shock absorber 1 to a suitable high damping coefficient proportional to the sprung speed ± V, vibration of the sprung body (vehicle body) is appropriately suppressed to improve steering stability and riding comfort. At the same time, the stroke side of the shock absorber 1 in the direction opposite to the direction of the sprung speed ± V at that time is set as a predetermined low damping coefficient to absorb the road surface input in the direction opposite to the stroke direction during vibration control. It is possible to further improve the riding comfort by preventing the transmission to the vehicle body.

(B) When the steering angular velocity is large As shown in FIG. 15b, the absolute value of the steering angular velocity ± θn |
When θn | once exceeds the absolute value | θc | of the threshold value ± θc, the roll generated by abrupt steering becomes excessive, so the roll control condition is switched to the ON state. The stroke side of the shock absorber 1, which is the same as the direction of the speed ± V, is switched to the ± Xmax position where the maximum damping coefficient is obtained, which suppresses the transient roll of the vehicle body by the high damping force exceeding the damping force in the ± Xhard position. It Then, after that, the steering angular velocity ± θn
Absolute value | θn | is the absolute value of a given threshold ± θc | θc |
Even if it falls below the level, the roll state continues,
The ON state of the roll control condition is maintained for a predetermined time T set in advance, and after the time T has passed,
When the direction of the sprung speed reverses, the roll control condition becomes O
The state is switched to the FF state, whereby the normal damping coefficient control state shown in (a) above is restored.

Thus, the absolute value of the steering angular velocity ± θn |
By predictively starting the roll control condition when θn | exceeds the absolute value | θc | of the predetermined threshold value ± θc, the control delay is eliminated and the sprung speed ± V direction in each wheel portion is eliminated. By switching the damping coefficient of each wheel on the basis of, the switching control of the damping coefficient corresponding to the actual rolling direction of the vehicle is performed. The feature is that the roll can be surely suppressed and steering stability can be secured.

Further, as described above, the damping coefficient of each shock absorber 1 is switched with reference to the direction of the sprung speed ± V of each wheel, so that the direction of the sprung speed ± V at that time is defined. It has a feature that the road surface input in the reverse direction is reliably absorbed with a low damping coefficient, so that the ride comfort can be secured when the vehicle body rolls.

Although the embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and there may be a design change or the like within a range not departing from the gist of the present invention. Included in the present invention.

[0042]

As described above, in the vehicle suspension system of the present invention, when the steering angular velocity is equal to or higher than the predetermined threshold value, the sprung portion of each wheel is spun after a predetermined time has elapsed from that point. Roll control for outputting a switching signal to each damping coefficient changing means in order to control the high damping coefficient on the stroke side of each shock absorber, which is the same as the sprung speed direction of each wheel until the speed direction reverses. The provision of the parts enables switching control of the damping coefficient corresponding to the actual rolling direction of the vehicle, which suppresses the rolling of the vehicle and ensures steering stability even with continuous steering such as slalom. It is possible to obtain the effect that the ride comfort of the vehicle during the roll control can be secured.

[Brief description of drawings]

FIG. 1 is a claim correspondence diagram showing a vehicle suspension device of the present invention.

FIG. 2 is a system block diagram showing a vehicle suspension device according to an embodiment of the present invention.

FIG. 3 is a cross-sectional view showing a shock absorber applied to the apparatus of the embodiment.

FIG. 4 is an enlarged sectional view showing a main part of the shock absorber.

5 is a sectional view showing a state of the first position, (a) is a sectional view taken along the line KK of FIG. 4, (b) is a sectional view taken along the line LL of FIG. 4, (c).
FIG. 6 is a sectional view taken along line N-N of FIG. 4.

6 is a sectional view showing a state of the second position, (a) is a sectional view taken along the line KK of FIG. 4, (b) is a sectional view taken along the line LL of FIG. 4, (c).
FIG. 6 is a sectional view taken along line N-N of FIG. 4.

7 is a sectional view showing a state of a third position, (a) is a sectional view taken along the line KK of FIG. 4, (b) is a sectional view taken along the line LL of FIG. 4, (c).
FIG. 6 is a sectional view taken along line N-N of FIG. 4.

FIG. 8 is a diagram showing a damping coefficient switching characteristic of the shock absorber.

FIG. 9 is a characteristic diagram of damping coefficient with respect to piston speed in the second position.

FIG. 10 is a characteristic diagram of damping coefficient with respect to piston speed in the first position.

FIG. 11 is a characteristic diagram of damping coefficient with respect to piston speed in the third position.

FIG. 12 is a variable characteristic diagram of the damping coefficient with respect to the piston speed of the embodiment apparatus.

FIG. 13 is a flowchart showing the operation flow of the control unit of the embodiment apparatus.

FIG. 14 is a flowchart showing an operation flow of the control unit of the embodiment apparatus.

FIG. 15 is a time chart for explaining the operation of the embodiment apparatus when the vehicle is traveling.

[Explanation of symbols]

 a damping coefficient changing means b shock absorber c sprung speed detecting means d steering angular velocity detecting means e damping coefficient control section f control means g roll control section

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[Procedure amendment]

[Submission date] April 30, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Figure 5

[Correction method] Change

[Correction content]

5 is a sectional view showing a state of a second position, (a) is a sectional view taken along the line KK of FIG. 4, (b) is a sectional view taken along the line LL of FIG. 4, (c).
FIG. 6 is a sectional view taken along line N-N of FIG. 4.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] Figure 6

[Correction method] Change

[Correction content]

6 is a sectional view showing a state of the first position, (a) is a sectional view taken along the line KK of FIG. 4, (b) is a sectional view taken along the line LL of FIG. 4, (c).
FIG. 6 is a sectional view taken along line N-N of FIG. 4.

[Procedure 3]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 3

[Correction method] Change

[Correction content]

[Figure 3]

Claims (1)

[Claims] 1. Damping of a structure which is provided between each wheel of a vehicle and a vehicle body and has a low damping coefficient on the reverse stroke side when one of the extension side and the compression side stroke side is controlled to the high damping coefficient side. A shock absorber having coefficient changing means, a sprung speed detecting means for detecting a sprung speed at each wheel portion, a steering angular speed detecting means for detecting a steering angular speed of the vehicle, and a steering detected by the steering angular speed detecting means. When the angular velocity is less than the predetermined threshold value, the damping coefficient changing means controls the shock absorbers to the optimum damping coefficient based on the sprung speed of each wheel detected by the sprung speed detecting means. When the steering angular velocity detected by the steering angular velocity detection unit, which is provided in the control unit and the damping coefficient control unit that outputs the switching signal, is equal to or more than a predetermined threshold value, After a predetermined time has elapsed from the point of time until the direction of the sprung speed of each wheel portion reverses, the stroke side of each shock absorber, which is the same as the sprung speed direction of each wheel portion at that time, is set to a high damping coefficient. A vehicle suspension device, comprising: a roll control unit that outputs a switching signal to each damping coefficient changing unit for control.